Blue Ridge Grass Bald (Roan Highlands Type)

Synonyms

Southern Appalachian Grass and Shrub Bald Ecological System (NatureServe 2015)

Distribution

Northeastern Tennessee (Unicoi, Carter, Johnson Counties) where restricted to selected exposed ridges (Big Bald, Round Bald, Jane Bald, Hump Mountain, Snake Mountain, Leander Mountain) within the Blue Ridge Mountains level III Ecoregion.

Vegetation Description

This small patch community occurs as open grassland with smaller patches of seeps, embedded dense ericaceous shrublands, called heath balds, and rock outcrops. This hummocky herbaceous vegetation of perennial grasses and forbs ranges in height from 0.1-1.0 m.

Physical Characterization

This community occurs in the Southern Igneous Ridges and Mountains, Southern Sedimentary Ridges, and Southern Metasedimentary level IV Ecoregions within the Blue Ridge Mountains level III Ecoregion (Comer et al. 2003). The grass balds occur on mountaintops, ridgelines, and adjacent slopes from about 1300-1850 m (4296-6100 ft), where it may occur on flat areas and adjacent 12-50 % slopes, except where rock outcrops may be 95%, of no particular aspect (Soil Survey Staff 2015). (sizes of examples???). Underlying geology is Precambrian metamorphic and igneous rock that varies from site to site: Big Bald is composed of Beech granite; balds of the Roan Mountain Massif are composed of Bakersville Gabbro and Roan Gneiss; and balds on Snake Mountain and Leander Mountain are composed of Cranberry Granite (Geology citation credible?). Soils are well-drained Inceptisols, composed of loamy residuum derived from igneous and metamorphic rock with a soil pH: 4.5-4.8 (Soil Survey Staff 2015).

Soil Series vary by site:

  • Big Bald: Burton-Craggey complex, windswept, 15 to 35 percent slopes, extremely bouldery
  • Roan Mountain Massif: Burton-Craggey complex, windswept, 8 to 35 percent slopes, extremely bouldery; Burton-Wayah complex windswept 15 to 50 percent slopes, stony; Wayah-Burton complex, windswept, 15 to 30 percent slopes, stony
  • Snake Mountain: Burton-Craggey-Rock outcrop complex, windswept, 30 to 95 percent slopes; Burton-Wayah complex, windswept, 15 to 30 percent slopes, stony; Greenlee very cobbly loam, 35 to 55 percent slopes, very stony; Porter’s loam, 15 to 30 percent slopes, stony
  • Leander Mountain: Edneyville loam, 12 to 45 percent slopes; Ashe-Cleveland-Rock outcrop complex, 50 to 95 percent slopes, extremely bouldery

Natural Processes

Grass Bald origin and maintenance is still largely speculation. The most recent theories suggest that ice age climatic change created alpine-like grasslands devoid of trees that have been kept open for thousands of years by a combination of megafauna, anthropogenic disturbance, and livestock grazing (Weigl and Knowles 1995; Spira 2011).

Dominant Plants

This community is dominated by the gramminoids Avenella flexuosa (wavy hairgrass), Danthonia compressa(mountain oat grass) and Carex pensylvanica (Pennsylvania sedge), though a diverse mixture of high-elevation endemic forbs grow in more scattered abundance (Spira 2011, Natureserve 2014).

Characteristic Plants

Angelica triquinata (mountain angelica), Calamagrostis cainii (cain’s reedgrass), Danthonia compressa(mountain oat grass), Krigia montana (false dandelion), Lilium grayi (Gray’s Lily), Sibbaldiopsis tridentata(three-tooth cinquefoil) (Natureserve 2014).

Restricted Plants (doublecheck)

Agrostis mertensii (arctic bentgrass), Calamagrostis cainii (Cain’s reedgrass), Carex misera (Wretched sedge), Carex pallescens (pale sedge), Epilobium ciliatum (hairy willow-herb), Gentiana austromantana(Appalachian gentian), Geum genticulatum (Bent avens), Geum radiatum (Spreading avens), Houstonia purpurea var. montana (Mountain bluet), Hypericum graveolens (Mountain St. John’s-wort), Hypericum mitchellianum (Blue ridge St. John’s-wort), Lilium grayi (Gray’s Lily), Packera schweinitziana(Schweinitz’s ragwort), Prenanthes roanensis (Roan mountain rattlesnake-root), Robinia hispida var. fertilis(Fruitful locust), Robinia hispida var. kelseyi (Kelsey’s locust).

Invasive Species

There are no severe-threat species currently affecting this community, other than common pasture weeds.

Community Variation and Subtypes

Carex pensylvanica Herbaceous Vegetation (CEGL004094)

Danthonia compressa – (Sibbaldiopsis tridentata) Herbaceous Vegetation (CEGL004242)

Associated Natural Communities

Blue Ridge Alder Bald, Blue Ridge Heath Bald, Blue Ridge Spruce-Fir Forest, Blue Ridge Northern Hardwood Forest, and Blue Ridge High-Elevation Outcrops and Seeps of various types.

Similar Communities

Blue Ridge Grass Bald (Southern type) and Blue Ridge Alder Bald.

Presettlement Distribution and Size

Presettlement size and distribution of balds is unknown because lack of grazing gives way to rapid succession by adjacent forests. Over the past century, more than half of known balds succeeded into forest due to lack of grazing on federal lands protecting balds (Spira 2011). However, studies of balds consider balds in Virginia, North Carolina, and Georgia as well as the Blue Ridge Grass Bald (Southern type) community collectively in statistics describing distribution and size, thus no description specific to the state of Tennessee specifically covers presettlement status of this community.

Present Status

Rare and threatened community.

Representative Sites

  • Tennessee, Unicoi County: Big Bald (Appalachian Trail)
  • Tennessee, Carter County: Roan Highlands (Appalachian Trail)

Threats

This community is under constant threat of succession by adjacent forests/shrublands and invasion by exotic species.

Management Considerations

The Appalachian National Scenic Trail, Cherokee National Forest, and land conservancies have protected many of the existing remnants of this community, but methods of maintaining open, grassy areas should be employed on every possible example, through mowing or grazing.

Future Research Needs

Further investigation of the origin of grass balds, especially through phylogeographic studies that may examine genetic flow between examples of the community, and presettlement distribution.

Previous Studies

Dozens of studies have floristically and ecologically examined Southern Appalachian balds of various types. Mark (1958) completed an ecological monograph of Southern Appalachian grass balds. Natureserve (2014) gives a good summary of distribution, flora, fauna, vegetation associations, and previous studies.

References

Comer, P., D. Faber-Langendoen, R. Evans, S. Gawler, C. Josse, G. Kittel, S. Menard, M. Pyne, M. Reid, K. Schulz, K. Snow, and J. Teague. 2003. Ecological systems of the United States: A working classification of U.S. terrestrial systems. NatureServe, Arlington, VA.

Geology available at Tennesse Spatial Data Server which can be found at http://www.tngis.org/geology.html which links to a USGS Water Resources Division site: http://water.usgs.gov/lookup/getspatial?geo250k Tennessee Spatial Data Server site notes: Thanks goes to Jim Julian for researching this improved geology layer from the Tennessee Division of Geology. **Note** - The Tennessee Division of Geology does not endorse this coverage, stating       this version is still incomplete and not fit for distribution.

Mark, A. F. 1958. The ecology of the Southern Appalachian grass balds. Ecological Monographs 28:293-336.

Mark, A. F. 1959. The flora of the grass balds and fields of the Southern Appalachian Mountains. Castanea 24:1-21.

NatureServe. 2014. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org. (Accessed: Februarty 17, 2015).

 Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil Survey. Available online at                                       http://websoilsurvey.nrcs.usda.gov/. Accessed [02/17/2015].

Spira, T. P. 2011. Wildflowers & Plant Communities of the Southern Appalachian Mountains & Piedmont. University of North Carolina Press: Chapel Hill.  521p.

 Weigl, P. D., and T. W. Knowles. 1995. Megaherbivores and Southern Appalachian Grass Balds. Growth and Change 26:365-382.

 

Checklist of Plant Species known from this community

See Mark (1959).